A sleeve cylinder exchangeable variable printer in which a printing images different in a vertical length are printed on a continuous web of paper is known from JP 2014-91301 A. Printing machines of this sort have been designed to exchange sleeve cylinders in a manual operation. Needs therefore arise to reduce the thickness of a sleeve cylinder as thin as possible in order to reduce its weight. The patent document mentioned above shows in FIGS. 4 and 5, and describes in connection therewith, an insertable printing plate which uses no plate clamping or winding bar but in which a grip leading end and a grip trailing end of the printing plate may be inserted simply in a groove on the sleeve cylinder for mounting the printing plate thereon.
This technique, however, in which the grip leading and trailing ends of a printing plate are inserted merely in a groove has been uncertain whether the printing plate is firmly held in position. While JP 2012-166569 A and JP 2002-326341 A show that press fitting members of metal, rubber, resin or leaf spring are added and press fitted into the groove for securing the printing plate, it has been difficult to ascertain that the press fitting members have been press fitted in a whole section in the width direction. Also, a need to increase the groove width by an amount of the thicknesses of such press fitting members has caused bounces (vibrations), noises and printing obstacles to occur in the groove while the plate cylinder is being rotated at high printing speed.
An object to be achieved of the present invention is to provide a printing plate holding apparatus which during a high speed printing operation reduces vibrations and noises caused in a groove for having a grip leading end and a grip trailing end of a printing plate inserted therein, which can fasten the printing plate with greater certainty, and which is suitable for a plate cylinder having such as a sleeve cylinder whose weight reduction is demanded.